The Basics of Wiring for Phones

For more than 40 years, Loren Wesley Vankirk has been working as an electrical contractor. He holds or is qualified for electrical licenses in nearly two dozen states. He possesses extensive experience with electrical systems including lighting, wiring, fire alarms, phones, and other low-voltage systems. Loren Wesley Vankirk leverages this knowledge to lead Vankirk Electric as CEO and owner.

Most phone wiring in residential homes consists of red, green, black, and yellow wires. These four wires are split into two pairs, one combines the red and green wire, and the other combines the yellow and black wire. The pairs are twisted around one another to prevent them from interfering with the other pair in any way. Each of these wires is also very thin, thus ensuring that they stand out from regular, thick electrical wires. 

When a phone line is placed into a building, only one pair of wires is needed. In most cases, the red and green wires are used for the phone line. Once the line is set up, the yellow and black wires remain unused. While this may seem pointless, having the second pair of wires keeps homeowners from having to rewire the entire home to accommodate a fax machine or other phone-related device.

In recent years, the popularity of modems, answering machines, and other phone-related devices has increased the need for six phone line wires in homes. This grants homeowners the ability to set-up one phone line and two additional devices, if necessary. The number of phone lines in a building is also higher in multi-home buildings or commercial buildings. In these cases, a property owner may have eight colored wires or more installed.